Toremifene
FARESTON
What it isA triphenylethylene selective estrogen receptor modulator, chemically adjacent to tamoxifen, for metastatic breast cancer in postmenopausal women.
Why this oneIt offers tamoxifen-class efficacy with a label distinction of its own; in practice it is a niche alternative where tamoxifen is problematic.
What limits itIt prolongs the QT interval — its label distinction from tamoxifen — and shares the class thromboembolic and endometrial risks.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Breast cancer (postmenopausal; indication section not provided — see flags) | Postmenopausal women | 60 mg QD | 60 mg QD until disease progression | 60 mg QD |
Renal PK of toremifene and N-demethyltoremifene similar in renal impairment; no specific adjustment stated
Hepatic Elimination half-life increased <2-fold in hepatic impairment (cirrhosis/fibrosis); exercise caution; no specific adjustment stated
Instructions
- Correct hypokalemia/hypomagnesemia before initiating; monitor electrolytes periodically
- Baseline ECG and as clinically indicated in patients at increased risk
- Periodic CBC, calcium levels, and LFTs; baseline and annual gynecologic examinations
Contraindications
- Congenital or acquired QT prolongation (long QT syndrome)
- Uncorrected hypokalemia or uncorrected hypomagnesemia
Cautions
- QT prolongation/torsade de pointes — avoid QT-prolonging drugs and strong CYP3A4 inhibitors; caution in CHF, hepatic impairment, electrolyte abnormalities
- Hepatotoxicity — Grade 3/4 transaminitis, hyperbilirubinemia, jaundice, hepatitis, NAFLD reported; periodic LFTs
- Hypercalcemia and tumor flare in bone metastases during first weeks — discontinue if hypercalcemia severe
- Uterine malignancy risk — endometrial cancer, hyperplasia, polyps reported; monitor high-risk patients
- History of thromboembolic disease — generally do not treat
- Rare leukopenia/thrombocytopenia — monitor counts in affected patients
Adverse reactions
- Most common: hot flashes (35%), sweating (20%), nausea (14%), vaginal discharge (13%), dizziness, edema, vomiting, vaginal bleeding
- Serious (≥1%): thromboembolic events (pulmonary embolism, thrombophlebitis), MI, ischemic attack
Pregnancy Category D — can cause fetal harm (embryo-fetal toxicity below human dose in animals); premenopausal women must use effective non-hormonal contraception
Lactation Unknown if present in human milk (excreted in rat milk) — discontinue nursing or the drug
NO BOXED WARNINGS
Classes and tags
Clinical profile
Mechanism of action: Toremifene ballicule
